Abstract
When muscles are damaged, the tears in the muscle fibers triggers an immune response and muscles experience inflammation. Inflammation increases WBC in the muscles to repair the micro tears. Muscle inflammation can be assessed by measuring the cross-sectional area (CSA) via ultrasound images. PURPOSE: To examine the effect of hydration status during recovery on muscle swelling after muscle damaging exercise. METHODS: Six recreationally active men (19 ± 1yr, 169.8 ± 8.3cm, 79.5 ± 11.7kg, Lean mass 58.6 ± 13.0kg, %body fat 28.3 ± 6.5%) completed two bouts of an identical muscle damaging exercise (DAM-EX) under a hydrated state and underwent a 3-day recovery period either under a hydrated or dehydrated state. The DAM-EX consisted of a total of 300 repetitions (10 sets x 30 repetitions) of unilateral maximal eccentric knee extensions. To control for the nutritional intake, participants were instructed to follow preplan diets focused on low-moisture content food for both conditions. Muscle ultrasound images of the rectus femoris of the damaged leg were taken prior to (PRE), and 24hr, 48hr and 72hr after the DAM-EX. All images were then de-identified and analyzed by the same examiner to eliminate bias and increase consistency. The CSA of the rectus femoris was measured using ImageJ software. RESULTS: Significant (p < 0.05) condition x time interaction effects observed for CSA. In the hydrated condition, CSA increased from PRE (5.08 ± 1.37cm2) to 24hr (5.88 ± 1.44, p = 0.005), 48hr (5.90 ±1.62, p = 0.007), and 72hr (6.34 ± 1.75, p = 0.002). In the dehydrated condition, CSA increased from PRE (4.95 ± 1.52) to 48hr (5.68 ±1.51, p = 0.004) and 72hr (6.12 ± 1.79, p = 0.02), with no change from PRE to 24hr. CONCLUSION: Our data indicates that unlike the hydrated condition, the muscle swelling does not significantly increase in the dehydrated condition until the 48hr post muscle damage. Given that the influx of immune cells to the injury site results in muscle swelling, the delay swelling in the dehydration condition may indicate a delay in the immune response, and thus this delay could potentially result in delay muscle functional recovery.
Recommended Citation
Walper, Sarah; Appell, Casey; Domonkos, Trinity; Olvera, Karina; Bernardino, Seth; Dunlap, Jalyn; Munger, Larry; and Luk, Hui-Ying
(2026)
"Delay in Increased Muscle Cross Sectional Area After Muscle Damage While Dehydrated,"
International Journal of Exercise Science: Conference Proceedings: Vol. 2:
Iss.
18, Article 123.
Available at:
https://digitalcommons.wku.edu/ijesab/vol2/iss18/123
Included in
Health and Physical Education Commons, Medical Education Commons, Sports Sciences Commons